JavaScript Developer I Certification Preparation
On August 4, 2020 I completed Salesforce Certified JavaScript Developer I Certification. The exam experience was very different compared to previous certifications as there was absolutely no references to official Salesforce documentations. It was purely JavaScript. The Certification is divided into two parts:
- Lightning Web Component Super Badge.
- JavaScript Developer I Multiple choice exam.
Which Part to Attempt First?
Both of the above criteria can be obtained in any order. Doing the exam first won’t make any difference as the exam doesn’t really focus on lightning web components (as of my time of writing this post). I believe that’s why Salesforce has introduced a super badge for this. What I would recommend is doing the super badge first will give you a head good start to prepare for the multiple choice exam as some of the steps of super badge are tricky which involves writing some pure JavaScript. So you will definitely go out of your way to get some steps working and learn some cool features of JavaScript. But its totally up to you which part you want to attempt first. If you are from a JavaScript background looking to get into Salesforce development then giving the multiple choice exam first is a good fit.
LWC Superbadge
I wont focus too much on the superbadge since this post mainly focuses on JavaScript multiple choice exam. Most of the information and steps are given in Trailhead for obtaining the badge. You can access the super badge from this link. You need to complete 4 modules on Trailhead in order to unlock the superbadge module. Module links:
Quick Start: Lightning Web Components
Lightning Web Components and Salesforce Data
The Superbadge has some good challenging steps and covers all the scenarios of web component development similar to a real word project! I would recommend not to really rush through the steps. Try to understand what is the ask, How many components you would need, Make a model of the components and then attempt the superbadge as a whole. Don’t worry about verifying the steps. If you have understood the requirements, you will eventually be able to knock these off. References and example recipes that may come useful during the superbadge:
JavaScript Developer I Multiple Choice Exam
As I mentioned above, This exam is different from usual Salesforce exams. The Trailmix is a good start but most of its references focuses more towards the superbadge. The exam consists of 60 questions with additional 5 non scored questions. You have total of 65 questions to be attempted in 105 minutes. The passing score is 65% which is about 40 correctly answered questions.
IMPORTANT!! Before we jump on the topics, Do make sure to go through the exam guide and make a note of the suggested resources there. Those are primary ones. I also found this preparation trail very helpful as it has example flash cards with example questions and suggested references. This module gives you an idea how the questions will look like. Make sure to take a note of all the suggested references there.
Topic Breakdown & Main Focus Areas:
Variables, Types and Collections 23%
Object, Functions, and Classes 25%
Browser and Events 17%
Debugging and Error Handling 7%
Asynchronous Programming 13%
Server Side JavaScript 8%
Testing 7%
Variables, Types and Collections (23%)
Data Types in JavaScript — Primitive, Composites and Special
Create and Initialize variables correctly
Demonstrate awareness of type coercion and its effects
Array methods, Data manipulations with arrays
JSON objects and methods
Sets and Maps
TypeOf , InstanceOf Operators
Strict mode — Behavior differences in strict vs non strict mode
Grammar types and Template literals
Decorators
Objects, Functions and Classes (25%)
Objects — Iteration, Enumeration, Object Properties such as Object Prototypes, Garbage collection, this keyword, Optional chaining, Object to primitive conversion, Global objects
Functions — Regular function declaration vs arrow functions, Function expressions, declarations
Classes — Inheritance, Static methods and properties, private and protected, Mixins, built in classes
Import & Export modules in JS
Loops and Iterations
Browser and Events (17%)
Event Listeners
History API — popstate, pushstate, replaceState etc.
Events — Event propagation, DOM visibility, Differences between bubbles composed
DOM Structure, DOM manipulation
Developer Console
Window API, Location API, Navigator API, Screen API
setTimeout, setInterval
Page Events
Debugging and Error Handling (7%)
Error Handling in JS — Try, Catch, Finally
Custom Errors — Overriding the Error class
Debugging
Control error handling flow
Debugging in browser with breakpoints, Debugger statements
String substitutions
Asynchronous Programming (13%)
Promise basics
Using promises, Promise methods
Asynchronous function
Combination of async-await
Promise chaining
Callback stack
Server Side JavaScript (8%)
NPM Modules, Package.JSON structure
NodeJS Basics
Frameworks — Which frameworks is suitable à Frontend vs Backend
CLI
Testing (7%)
Console commands
Assertions
Testing Implementation — False positives vs False negatives
Black Box Testing vs White Box Testing
Jest basics
Recommended References
I found MDN and JavaScript.info the most helpful in my preparation. Also the exam guide on Trailhead mostly have references to these two sites. But its your personal choice which site you feel comfortable with. There are some other good sites like Udemy, PluralSite and SitePoint which you can also refer to. Make sure to go through the official Exam Guide, Trailmix and Study Trail as well.
Conclusion
If you are still unsure on how specific functionalities work in a real time scenario its always better to go to do those in practice in your local browser console and refer some videos on YouTube with detailed examples. It took me some time to understand the Events and Asynchronous structure so I decided to create some sample apps in my local and test various combinations. At the end of the day you have to make sure there is absolutely no confusion. As far as the exam goes most of the questions will be code output based, so you really need to manage time as well as stay focused till the very end. Good thing about this exam is you have four options and one of them is the right one. Try to understand the scenario, look at the options and then try to filter down the best possible outcomes. Don’t rush through the preparation and take your time. Learning matters!
